Longtime USA Hockey executive and U.S. Olympic men's hockey general manager Jim Johannson died unexpectedly Sunday at age 53, shocking the sport less than three weeks before the start of the Pyeongchang Games.

Johannson died in his sleep at his home in Colorado Springs, according to USA Hockey. His death came in the midst of the most high-profile role in his career: putting together the U.S. men's Olympic hockey team without NHL players going to South Korea, a position he relished after doing so at several world junior and world championships.

"He had a couple of the greatest days of his life at USA Hockey recently to be able to call all these guys that never thought in their lives they'd play on a U.S. Olympic hockey team, and he got to tell them that they realized a dream," USA Hockey execute director Pat Kelleher said by phone. "I think that meant as much to Jimmy as it did to any of the players."

With the NHL out of the Olympics for the first time since 1994, Johannson was excited about putting together a 25-man roster that would include "25 great stories." He picked Tony Granato as coach and on Jan. 1 unveiled a diverse roster made up of players from European professional leagues, the American Hockey League and the NCAA.

Johannson was proud of the unheralded roster, one that will now try to capture a gold medal for him.

"I think it would be huge," former USA Hockey executive director Dave Ogrean said by phone. "If we ever had a `Win one for the Gipper' moment, this is it."

It's unclear who would be in charge of choosing any potential injury replacements if needed. The U.S. opens the Olympics Feb. 14 against Slovenia.

The talent pool now and in other tournaments is deeper in part because of Johannson, who has overseen the growth of hockey in the U.S. beyond the "Miracle On Ice" in 1980. Retired American-born forward Jeremy Roenick said, "USA hockey is a world power now because of people like Jimmy Johannson."

The U.S. won 64 medals, including 34 gold, in major international competition during Johannson's tenure. The Americans in particular became a perennial threat to win the world junior championship, showing the program's improvement at the youth levels.

Carolina Hurricanes president Don Waddell said Johannson "has been a driving force in making both the USA Hockey men's and women's programs into consistent winners, and 2015 gold-medal-winning world junior coach Phil Housley said Johannson "grew our game to new heights."

"In building the teams that achieved so much success for USA Hockey, Jim Johannson had a sharp eye for talent, a strong sense of chemistry and a relentless pursuit of excellence," NHL commissioner Gary Bettman said. "As we mourn his loss, we will remember the positive outlook Jim brought to his tireless efforts to advance USA Hockey."

Johannson, who played for the U.S. at the 1988 and 1992 Olympics, began working for USA Hockey in 2000 after spending five years as the general manager of the Twin Cities Vulcans in the United States Hockey League. He was promoted to assistant executive director of hockey operations in 2007, overseeing the organization's efforts in fielding teams for international competition.

He played college hockey at Wisconsin and helped the Badgers win the NCAA championship as a freshman. He was selected by Hartford in the seventh round of the 1982 draft and although he never played in the NHL, he was respected and well-liked by those all over hockey.

"We lost a true friend in Jim Johannson today," Granato said. "He was so compassionate and as loyal a friend as you could have. He was the ultimate teammate. I am deeply saddened and shocked and sorry that he is no longer with us. He was a special human being. Please pray for Jim's wife and daughter, Abby and Ellie."

Kelleher said USA Hockey would think about ways to pay tribute to Johannson at the Pyeongchang Games after grieving this loss.

"Today it's really just trying to help his family as best as we can and really just try and honestly put one foot in front of the other," Kelleher said. "We'll have to see what we can do to try and honor him in some fashion."